Micrometer-gage.



No. 839,943. PATENTED JAN. l, 1907..

E. A. MARSH.

MICROMETBR GAGE.

APPLIUATION FILED JULY'I.19oe.

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-PATENTED JAN. I, 1907..

No. 839,943. v

E. A. 1v1/MSH.` MIGROMBTBR GAGE. APPLICATION FILED JULY "l, 1906.

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THE NDRRIS PETERS CO., WASHINGTON. D. C.

. UNITED STATES PATENT OFFICE.

MICRONIETER-GAGE.

, Specication of Letters Patent.

Fatented Jan. 1, 1907.

`Application filed July 7,1906. Serial No. 325,143.

To all whom t may concern: p

Be it known `that I, EDwARDA. MARSH, of Newton, in. the county of Middlesex and `State of Massachusetts, have invented certain new and useful Improvements in Micrometric. Gages, of which the following is a i speciiication.

This invention relates to micrometric measuring-instruments, and is designed to provide an improved form of caliper or gage by which minute differences in the dimensions of small mechanical parts` may be detected.

In the manufacture of large numbers of parts ofmechanisms which must be as nearly uniform as possible to secure interchange- .\ability, such as in theparts of watch-move- 1 ments, it is essential to provide instruments of.sufiicient delicacyto detect exceedingly. 120

slight `variations from the standard dimen- My object has been to -secure such an instrument, and by the present invention I have provided one which is capable of measuring small `dimensions with accuracy and 1s .Y of convenient formand sizeandsimple yand .durable in construction and accordingly capable of being made and sold at a small price. `l.In its essential'` elements my improved` measuring instrument'consists ofv two jaws or lthe measuring-jaw. lThecam is provided 'with `a circular series of. graduation-marks,

which are proportional to the .eccentricity of the cam at corresponding points and serve to ymeasure onia greatly enlarged scale the movement of the measuring-j aw. These elements and other features `areillustrated in detail in `the accompanying drawings and hereinafter .described andclaimed.

- In .thedrawings, Figure 1 represents an I elevation of a measuring instrument embodying the-principles of my invention. .represents a section, on an enlarged scale,

Fig. 2

on line 2 2 of Fig. 1, showing` all but the extreme right-hand vend of vthe instrument. Fig. 3 represents a sectional view showing the parts omitted in Fig. '2. 4sents a cross-section on line A 4 of Fig. 1.

Fig. l5 represents a section on line 5 5 of Fig.1.

Fig. `6 represents-an elevation as seen .from

Fig. 4 reprei `the .rear of Fig. 1. Fig; 6a represents a perspective view of the stop member, shown. in Fig. 6. Fig. 7 represents a view similarito Fig. 1 of a modification of the instrument designed for special work. Fig. 8 represents a longitudinal section of Fig. 7. Fig. `9 represents across-sectional view on line 9 9 of Fig. S looking toward the right. Figs. 10 and 11 represent a section and an elevation, respectively, of the frictional actuator for the cam.

The same reference characters indicate .the same parts in all the iigures.

Referring to the drawings, Figs. 1.to 6, inclusive, show a form of the instrument designed for general work. This consists of a body portion or holder a, which may beheld in the hand of the user or set upon a pin b, which is pivotally mounted ina base c, upon which it may beheld in any position.

The body portion is provided'with an'out- `wardly-extendingv arm a, in the opposite sides of` which are formed guideways d and e, respectively. vIn the guideway d is set a slidable bar f, which is held in place by a cover-plate g, `screwed to the arm a.,while in the guideway e is set a slide h, held inplace by the overhanging sides of theguideway e.

cThe slide h is .normally held stationarygand has a squarel edge h, Fig.. 6, on its outeriend,

-whichserves as a normally stationary caliper` jaw or abutment, while the barf carries upon its end a cooperating movable caliper jaw or gage member fi. The member i has a square edge i', which is adapted to abut against the edge h of the abutment h. i

- Secured upon a stud j is a disk kfwhich has an eccentric periphery no two parts of which are at the samedistance from the axis of the stud. Beginning with the .most extended portion c each successive point ofthe periphery of theA cam is nearer `the axis, so that the periphery has the form ,of an involute curve or spiral beginning at lc: and ending at k2 on the same radius. The stud j is journaled in the body portion a and passes through a slot f in the slide-bar f. This-bar extends entirely across the cam and` has a pin [engaging the periphery of the cam. I/Vhen the cam is in the position shown in Fig. 1 with its shoulder between the points k and k2 in engagement with pin l, the Vmovable j'aw 'i is in its most remote position from the abutment h, and rotation of the-cam in the directionof the arrow moves it toward the abutment. On the face of thecam k IIO adjacent its periphery are put radial graduation-marks, which are arranged to represent fractions of any desired unit, such as a millimeter, &c., and by reference to the pin Z serve to show the distance by which the measuring-jaws are separated. As pin Z moves only from k2 to 7c in a complete rotation of the cam while a large number of graduations spaced sufficiently far apart to be easily read may be placed upon the disk, it is evident that minute fractions of the distance tlIlough which the jaw moves are determina e.

The movable jaw is adjusted to regulate its distance from the abutment by a screw m, threaded into a reduced extension f2 of the slide f, and is clamped in any position of adjustment by screws n, extending through a split portion of the jaw which embraces the extension f2. The abutment h is also adjustable to permit of objects having a large range of size being measured. It is to permit of such adjustment that the abutment is mounted slidably in the guideway e. lt is held normally in one position by means of a stop o, ivoted at o and having several arms p, whic are of different lengths. The stop member is movable, so that any one of the stop-arms may be brought into engagement with the end of the abutment, and the distance of the latter from the movable jaw depends on which of the stop-arms engages it.

contact.

cesslve stop-arms 1s preferably one unit, or

Preferably when the longest arm p engages the abutment the jaws maybe brought into The difference between the sucthe amount of movement effected by a com- For turning the cam I` provide a lingermember consisting of a sleeve t, having a ilange t', adapted to be grasped and rolled between the thumb and finger of the user. This sleeve fits upon a hub k3 of the disk and is held thereon by a screw u and washer u. There is a certain amount of friction between the sleeve and hub, so that the disk may be turned by the former when the resistance is not great g but the frictionis so slight that the sleeve will slip as soon as any considerable resistance 1s encountered. Thereby when an article being measured 1s grasped between the jaws the movement of the latter will be stopped before any pressure suflicient to indent the object and vitiate'the result or to injure either jaw or the cam can be applied.

tact with the part i.

Friction is produced by a spring-.tongue t2, formed on the sleeve, as shown in Figs. 10 and 11.

An additional dial v is secured upon the stud y' on the opposite side of the body portion from the cam 7c, this dial having graduations which by reference to a fixed pointer v serve to indicate the size of the object being measured when a reading on the cam-dial k cannot conveniently be obtained.

It will be noted from Figs. 2 and 3 that the dial i) and stop member o are set into recesses in the body, so that their outer surfaces, as well as the surfaces of the measuring-jaws and the body portion, are all in the same plane without any part except the pointer c projecting beyond such plane. This permits the instrument to be used in occasional special conditions where the parts to be measured consist of a small projection extending from a piece of large area.

If desired, the instrument may be made with provisions for varying degrees of sensitiveness-that is, the rate of change of eccentricity may be made different in different parts of the cam, so that in certain positions of the cam more minute differences of size may be detected. In Fig. 7, which is on a somewhat enlarged scale, the cam is shown as having the part between the points lc and the mark h4 with less rapidly diminishing radii of curvature than the remaining portion of the cam. Thus this quadrant of the cam from 7c to c1 measures in hundredths of a unit, while on the other portions of the cam the figures read in tenths, and the re cession of the periphery in passing from 7c to h4 is no greater than going from 164 to k-that is, three-tenths of a unit. This is to enable the instrument to be used readily for two different classes of measurement, such .as measuring the thicknesses and widths of watch-mainsprings. The form of the invention shown in Fig. v7 is particularly designed for the special work of measuring mainsprings of which the thicknesses do not exceed three-tenths of a millimeter, and when the movable gage member i, is within .threetenths of a millimeter of the abutment 7i some part of the cam portion k 761 is in con- When this part of the cam is operated, its movement by one of the divisions will move the member 'i one-hundredth of a millimeter, and when the other portion of the cam is adjacent member i the IOO ICS

IIO

n land is adjusted by a'screwm.' The movable jaw i travels in the same groove and is held against the cam c by means of a spring g. The disk is provided with a hub portion 7c3, which turns about a stud j, fixed in the body a instead of being rotatable therein, as in Fig. 2. The frictional sleeve t, mounted upon the hub 7c3, is the same as that already described. Although with this device very fine measurements can be secured with great accuracy, the device is yet very simple and inexpensive.

I claiml. A micrometric. measuring instrument comprising relatively fixed and movable jaws, and a graduated disk having an eccentric cam-shaped perimeter engaged with the movable jaw. A

2. A micrometric measuring instrument comprising relatively fixed and movable' jaws, and a graduated disk having a cam-v shaped perimeter engaged with the movable jaw, said camy portion being of constantly varying eccentricity proportional to the graduations of the disk.

3. A micrometric measuring instrument comprising relatively lfixed and movable jaws, and a graduated disk having a spiral cam portion in one plane engaged with the 'movable j aw.

4. A micrometric measuring .instrument comprising a relatively fixed abutment, a jaw movable toward and from said abutment, and a graduated flat disk having its periphery formed as a cam engaged with the jaw, the abutment being adjustable to vary its distance from the jaw.

5. In a micrometric measuring instrument, Va spiral cam having a plurality of portions of regularly-changing eccentricity, the rates of variation in the eccentricities of the several portions being different, and the cam having reference graduations on each of the different portions, which represent different units proportional to the various changes-of eccentricity.

6. In a micrometric measuring instrument, a spiral cam having a plurality of portions of regularly-changing eccentricity, the rates of variation in the eccentricities of the several portions being different, and the cam having separate sets of graduations reading in terms of the various differences in eccentricity.

7. A micrometric measuring instrument comprising a graduated disk having its periphery formed as a spiral or snail, a xed abutment, a member movable in a straight line toward and from said abutment, and engaged with the periphery of said disk, and a spring tending to hold said movable member against the disk.

8. A micrometric measuring instrument comprising a graduated disk having its periphery formed as a spiral or snail, a xed abutment, a member movable in a straight line toward and from said abutment, and engaged with the periphery of said disk, and a spring tendingto hold said movable member against the disk, the abutment being adjustable in the line of movement of the member. 9. In a micrometric measuring instrument, a rotary disk having graduations and formed with its periphery gradually approaching the pivot from the most extended point, in an involute curve, and a caliper-j aw or gage member rectilinearly operable by said disk; one portion of the disk periphery being of less abrupt curvature than the rest, whereby a corresponding angular movement of this portion of the disk will produce less motion of the gage member.

10. In a micrometric measuring instrument, a stationary abutment, a gage member movable toward and from said abutment, a

cam-disk for moving said memberV and having a scale for indicating the distance thereof from the abutment, and a finger-piece for moving said disk, having a frictional engagement therewith and adapted to slip when a resistance is encountered of greater force than the friction.

l1. In a micrometric measuring instrument, a stationary abutment, a gage member movable toward and from said abutment, a cam-disk for moving said member and having ascale for indicating the distance thereof from the abutment, a coaxial projection on said disk at the pivot thereof, and an operating member frictionally engaged with said projection for turning the disk, adapted to sli when a resistance of greater force than the fliction is encountered and prevent injury to the parts and to insure uniform and safe pressure.

12. In a micrometric measuring instrument, a stationary abutment, a gage member movable toward and from said abutment, a cam-disk for moving said member and having a scale for indicating the distance thereof from the abutment, a hub on the disk, and a sleeve mounted on said hub with a frictional engagement, adapted to be grasped and turned manually for revolving the disk, and to slip when the movable member is arrested.

18. A micrometric measuring instrument comprising a support or body, a normally stationary abutment, a movable gage member, a rotaryV cam-disk engaged with said gage member for moving it relatively to said abutment and having graduations for measuring the amount of such movement, and a graduated dial connected to said disk and movable therewith.

14. A micrometric measuring instrument comprising a support or body, a normally stationary abutment, a movable gage member, a rotary cam-disk on one side ofthe body engaged with said gage member for IOO IlO

-zo ,with said g-age member .for 1moving :it vrelaimoving ,it irelatively to said abutment andi! havinggraduations for measuring the amount of sueh` movement, and al gnaduated; dial oon-` 'neoted to said disk on, the' opposite side of; the

5 body from the' disk-.and i movable therewith. 1'5. A miorometrio `measuring 'instrument eomprisingfa supporter body, a normally station-ary adjustable abutment, a :movable gage .memben a rotary 10am-disk engagedy 1o 'with said ,f gage member :for :moving .fit irelatively to saidV abutment and v having gradua-l tions for: measuring they :amount Ofsueh move- ,.ment, and astop, against Whiohsaidabut- :ment istadaptedtto bear,1displaoeabletoiper-g I 5 miti shifting of` said: abutment. ,16. A -mierometrio i measuring 1 instrument l feomprisingaa support orbody, Ia'normally; stationary adjustable abutment, a movable gage ;member, a rotary `-cam-disk engaged]` tively y to l said abutment and having ggradua ,tions lfor measuring the .amount :o'f suoh movement, -a plurality off stops displaoeable lto permit eaoh to engage separately withV the;

2.5 abutmentandffadaptedto sustain the-abut- Iment, in differenti positions, and: means 1 tendi ing to l1old= ,the` abutmentiin engagementwith the nearest stop. l 17,. A lmierometrio measuring :instrument vmeasuring the amountof -suehf movement, `a ypivoted memberhavin .aplurality offstoparms of dierenti-lengt s=movable `.to bring ment againstg the nearest `stop-arm.

f gage member,a rotary oamfdisk engaged with said Agage member for moving itp-relatively to said abutmentfand having `graduations for any single arm adjacent the abutmentand `yielding means Atending lto shold =,the :abut- 4o 18. AA ,mioromet-rio :measuring f instrument comprising a movable jaw, a normallystationary j aW or abutment adjustabletoward andifrom saidfmov-able ijaw, a @am engaging Asaid Ymovable jaw Vfor 1moving sit :toward ythe abutment, afstop for limiting the movement -of the :abutment :away fit-rom the imovfable jaw, and a spring tending to holdithe -jaws separated, with .the abutment iin Contact fwith; said; stop and the 'movable jaw [in engagement ,with the 1 disk.

yIn testimony .whereof EI have waliiXed :my signature ini. presence' off two'vvitnesses.

'EDVVAR'D A. MARSH.

Witnesses: l i

A.. 1C. RATIGAN,

H. L. ROBBINS. 

